In servo stepper motion control, the first practical decision is whether you're repairing an existing axis or building a new one. The Unisys replacement servo motor and the Yifeng 1kW AC servo package sit on opposite sides of a $437 price spread. That spread isn't just a budget gap; it points to two different jobs.
Quick Verdict
If your machine already has a working controller, the Unisys replacement is the lower-cost way to go. If you are starting a CNC or automation axis build, the Yifeng package is the more complete route.
Comparison at a Glance
| Product | Listed Price | Relative Price Bar | Key Details |
|---|---|---|---|
| Unisys Replacement Universal Magnetics Servo Motor w/ Encoder and Board 84735-01 | USD 99.99 | Servo motor with encoder and board; New - Open box | |
| Yifeng Brake AC Servo Motor 1KW 4NM NEMA32 Drive Amplifier 220V CW/CCW Z Axis Milling | USD 536.99 | 1kW brake servo motor; NEMA32 drive amplifier; 220V input; 2500 RPM; 12 N.m peak torque |
Where Each Product Wins
Where the Unisys servo motor wins: This is the more focused replacement. It carries a clearly defined part number and sits at the low end of the price spread, so it suits a repair that doesn't need a whole new control package.
Where the Yifeng servo package wins: This is the more complete new-build path. It brings the motor and amplifier together, so you can start an axis with the main pieces already matched in one listing.
Product Notes
Unisys Replacement Universal Magnetics Servo Motor w/ Encoder and Board 84735-01
For anyone repairing a machine rather than starting from scratch, this listing is the more focused buy. It lands at the low end of the price spread, and the part numbers make the intended use clear: the motor carries part 84735-01, the board carries 90795-01, and the MPN 2831589-675 gives you a specific reference to match against your existing system. That is useful when you already have the drive and wiring and simply need a compatible servo motor with encoder. The limitation is the condition and scope. The listing is New - Open box, so you are buying a unit that was opened for pictures, not a sealed retail box. You should plan to provide the surrounding control hardware yourself. If your goal is a low-cost replacement for an established setup, this is the one to keep on the bench.
Yifeng Brake AC Servo Motor 1KW 4NM NEMA32 Drive Amplifier 220V CW/CCW Z Axis Milling
If you are building a new axis, the higher end of this price spread changes the shape of the project. The listing specifies a 1kW AC servo motor with brake, a NEMA32 drive amplifier, and 220V input compatibility, and the model 80st-m04025-BZ gives you a specific part to research. The control modes span position, speed, and torque, and the drive supports MODbus with RS485 as the default interface, so it can fit a typical CNC or automation controller setup. The limitation is the upfront cost and the setup details: the price is materially higher, the input voltage is single or three-phase 220V, and if you prefer RS232 or a longer cable than the 3m listed, you need to coordinate those options. For a self-contained start on a Z-axis milling build, this is the more complete offer.
Final Choice by Use Case
- Choose the Unisys Replacement Universal Magnetics Servo Motor when you are replacing an existing motor in a machine that already has a working controller. At $99.99, it's the lower-cost way to put the Unisys replacement motor on the bench.
- Choose the Yifeng AC Servo package when you need a coordinated new axis for CNC milling or automation. At $536.99, it's the more complete way to bring the motor and amplifier together.
